Plasma arc torches, also known as electric arc torches, are commonly used for cutting, marking, gouging, and welding metal workpieces by directing a high energy plasma stream consisting of ionized gas particles toward the workpiece. To make a cut perpendicular to the workpiece, the plasma arc torch is generally maintained perpendicular to the workpiece and at a predetermined height from the workpiece to maintain a desired arc voltage for optimal cutting operation.
When a bevel or angled cut is desired, the plasma arc torch is rotated or tilted to define an angle equal to the desired bevel cut angle. When the plasma arc torch is in a tilted position, controlling the position of the plasma arc torch relative to the workpiece becomes difficult and time consuming. The torch height and the thickness of the workpiece affect the arc voltage, which in turn affects the cut quality. After the plasma arc torch is rotated, the arc voltage between the plasma arc torch and the workpiece changes from the desired arc voltage due to the changed thickness of the workpiece along the desired cutting surface. Therefore, the torch height needs to be adjusted to maintain the desired arc voltage. Typically, the torch height is adjusted by raising or lowering the plasma arc torch vertically and in a direction perpendicular to the workpiece. When the plasma arc torch is raised or lowered, however, the longitudinal axis of the titled plasma arc torch is shifted away from the desired cut location, resulting in a bevel cut at the wrong location. Offset compensations are typically used to move the plasma arc torch back to the desired location. The procedure of adjusting the torch position while maintaining the torch height is time consuming and requires much setup and testing for accuracy.